Carlsbad Desal Plant - Home the carlsbad desalination project, desalination, desal, carlsbad desalination, san diego county water authority, encina power plant, city of carlsbad public works, poseidon, poseidon water, Claude "Bud" Lewis, bud lewis The Carlsbad Desalination Project is the largest desalination plant in the Western Hemisphere. Located in Carlsbad, California it converts sea water into 50 million gallons of drinkable water per day. Learn more at our site or come for a tour.